Moving grate assembly



y 1963 F. VOLLHARDT ETAL 3,095,839

MOVING GRATE ASSEMBLY Filed Oct. 4, 1961 2 Sheets-Sheet 1 jnvemm's F Ut \/O 'IhARd c joAChi/"I (Bev y 2, 1963 F. VOLLHARDT ETAL 3,095,839

MOVING GRATE ASSEMBLY Filed Oct. 4, 1961 2 Sheets-Sheet 2 United States Patent M Kreis Gottingen,'Germany, assignors to Schmidtsche Heiss'dampf-Gesellschaft, Kassel wilhelmshohe, German y Filed Oct. 4, 1961,'Ser. No. 142,954

4 Claims. (Cl. 110-40) This invention relates to a moving grate assembly for a furnace, sintering apparatus, or the like. In particular,

this invention is an improvement upon the moving grate assembly disclosed in thenow abandoned copending application of Fromut Vollhardt, Serial No. 13,229, filed March 7, 1960, for Moving Grate Assembly.

In the aforesaid application, a moving grate assembly is disclosed having a plurality of-individual grate pallets movable on an endless track. The pallets abut each other and fill the upper reach of the track so that when a pallet is added to the inletend of the-upperreach, it pushes the entire line of grates and discharges a grate from the outlet end of the upper reach. This discharged grate slides down the lower reach of the track and is then lifted to the inlet end of the upper reach.

The object of this invention is to improve upon the construction of the aforesaid application so that the wear and tear on the grate is minimized.

!In general, this and other objects of the invention are obtained by forming each grate pallet as a carriage carrying a row of slot-ted grate bars held in the carriage by a shaft passing through the aligned grate bar slots. As the carriage is discharged from the outlet end of the upper trackway reach, it falls to the lower reach and travels along the lower reach in inverted position. The row of individual grate bars hangs vertically downward from the inverted carriage because each slotted grate bar slides across the holding shaft. As the carriages are lifted from the lower reach to the inlet end of the upper reach, the carriages are righted. However, the grate bars are inverted so that the top side of each bar which has been heated by the previous passage through the firebox now becomes the lower side of the grate ban entering the firebox while the previously cooled bottom side now is the upper side adapted to receive the fuel being burned in the furnace.

The grate bar assembly of this invention has the advantage in that it increases the effective life of the grate as used in the moving grate assembly.

Another feature of this invention is in that the cam driven arm for lifting the grate carriage from the lower to the upper traclwflay reach has a roller on its free end adapted to engage the carriage to be lifted.

Another feature of this invention lies in that the row of grate bars on each carriage, when being pushed into the inlet end position of the upper reach are passed through a tank filled with a cooling agent such as Water. This inlet end position is immediately in advance of the fuel hopper. The lower sides of the grate bars which were heated in a previous passage through the firebox are then cooled in the tank. The track-way is depressed at this position so that the lower sides of the grate bars can enter the tank. This feature, insofar as it is not desirable for other reasons, has the advantage of further cooling the grate bars when they have not been adequately cooled during their travel over the lower reach of the trackway. The slot in each grate bar has a width greater than the thickness of the holding shaft in the carriage so that the grate bars can drop down into the cooling tank.

The means by which the objects of the invention are obtained are described more fully with references to the accompanying schematic drawings, in which:

3,095,839 Patent ed July 2, 1963 FIGURE 1 is a front elevational view of the moving grate assembly;

FIGURE 2 is a cross-sectional view taken on the line II of FIGURE 1;

FIGURE 3 is a partial front elevational-view showing the modification of the invention-with the cooling tank; and

FIGURE'4 is a partial cross-sectional the line IIII of FIGURE 3.

As shown in FIGURE 1, a moving grate assembly'd is composed of an endless trackway having an upper firebox reach 2 and a lower return reach 3. The individual grate carriages 5 each have a shaft 6 extending between the" side walls 36 of the carriage. A row of individual grate bars 7 is mounted in eachcarriage, each grate bar having a slot 31 with the shaft 6 extending through the alignedslots. Eachcarriage is mounted on'wheels 25 which ride in the trackway. The side walls 36 are connected by means of crossbeams 35 for supporting the grate view taken on bars 7.

The upper reach 2 of the endless trackway is filled with a line of carriages. At the outlet end of the track, the discharged carriage falls to the lower reach over which it travels inverted. At the same time, the individual grate bars 7 slide on the shaft 6 and hang vertically downward. At the opposite end of the lower reach, there is a rotating shaft 26 which cam drives an arm 27 so that the free end of the arm will engage the carriage 28 for lifting the carriage up over the track portion 29 and into the inlet position 9 of the upper reach 2, the carriage 5 being then righted on the upper reach.

At the same time, the grate bars 7 are laid back in the carriage in inverted position so that the side of the grate bar which was carrying the fuel and heated in the previous passage through the firebox now becomes the lower side of the grate bar which does not carry fuel in its passage through the firebox. In other words, each grate bar has been turned A roller 33 is secured to the free end of cam driven arm 27, this roller being engageable with the carriage 28 for lifting the carriag As shown in FIGURES 3 and 4, a cooling tank 34 is mounted beneath the upper reach of the trackway immediately in advance of the fuel hopper. This tank is filled with a cooling agent, the depth of which can be maintained by conventional means. Each grate bar in the row of grate bars in the carriage has its lower side passed nthrough the cooling agent, this lower side being the side which was the upper heated side in the previous passage of the carriage through the firebox. The upper reach is depressed at this position in the form of a slide. This is done by connecting the parallel tracks of the upper reach 2 by means of crossbeams 37. Hence the crossbeams 35 of FIGURE 2 become unnecessary. FIG- URE 4 also shows a row of individual grate bars 7 as positioned during their movement through the firebox.

Slots 3.1 in the grate bars are wider than the thickness of shaft 6 so that the grate bars can drop into the cooling agent in tank 34.

As indicated in FIGURE 3, and as required by the construction of the cooling tank, the upper reach trackway can first run horizontally and then rise slightly behind the tank, or it can be horizontal throughout its entire length. When desirable, the cooling tank 34 can be omitted so that the grate bars returned to the inlet position of the upper reach have more or less hot lower sides which contribute to the preheating of the combustion air passed upwardly through the grate bars into the firebox.

Having now described the means by which the objects of the invention are obtained,

We claim:

1. In a moving grate assembly for a furnace having an endless trackway with an upper firebox reach and a lower return reach, a plurality of individual grate carriages mounted on said trackway, said carriages abutting each other in the upper firebox reach, a row of grate bars mounted in each' carriage, respectively, and means for lifting a carriage from the lower return reach of the trackiway intoithe inlet end position of the carriages on the upper firebox reach for pushing the carriages along the upper reach and thereby discharging a carriage from the bars in said carriage so' that the grate bars slide the length of said slot on said shaft and hang vertically from said carriage when on said lower return reach, and said means for lifting a carriage into the inlet end position on the upper reach including a cam driven arm for pushing a carriage upwardly around the traekway portion at said inlet end to right said carriage on said inlet end portion, and simultaneously invert said grate bars in their position within saidcarriage so that the previous firebox 4 passage upper grate bar surfaces now are the lower grate bar surfaces.

2. 'In a moving grate assembly as in claim 1, further comprising a roller on the free end of said cam driven arm for engaging and pushing a carriage.

3. In a moving grate assembly as in claim 1, further comprising a cooling agent tank beneath the grate bar entrance end position on said upper reach and adapted to be located in advance of the fuel feed to said upper reach, and slide means depressing said upper reach at said tank for'passing the lower sides of said grate bars through the cooling agent in said tank.

4. In a moving grate assembly asin claim 3, said slot in each grate bar being wider than the thickness of said shaft for permitting the lower sides of said grate bars "to drop into the cooling agent in said tank.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A MOVING GRATE ASSEMBLY FOR A FURNACE HAVING AN ENDLESS TRACKWAY WITH AN UPPER FIREBOX REACH AND A LOWER RETURN REACH, A PLURALITY OF INDIVIDUAL GRATE CARRIGAGES MOUNTED ON SAID TRACKWAY, SAID CARRIAGES ABUTTING EACH OTHER IN THE UPPER FIREBOX REACH, A ROW OF GRATE BARS MOUNTED IN EACH CARRIAGE, RESPECTIVELY, AND MEANS FOR LIFTING A CARRIAGE FROM THE LOWER RETURN REACH OF THE TRACKWAY INTO THE INLET END POSITION OF THE CARRIAGES ON THE UPPER FIREBOX REACH FOR PUSHING THE CARRIAGES ALONG THE UPPER REACH AND THEREBY DISCHARGING A CARRIAGE FROM THE EXIT END OF THE UPPER REACH TO RIDE INVERTED ON SAID LOWER REACH, THE IMPROVEMENT COMPRISING MEANS FORMING AN ELONGATED SLOT EXTENDING PARALLEL TO SAID UPPER FIREBOX REACH IN EACH GRATE BAR, SHAFT MEANS EXTENDING THROUGH 